1. Technical Field
The present invention relates in general to a disk drive unit and, in particular, to an improved system and method for limiting a range of motion of an actuator in a hard disk drive.
2. Description of the Related Art
It is commonly known that a hard disk drive is widely used as a storage means for data in a computer system. FIG. 8 depicts an exemplary structure of a hard disk drive. For a hard disk drive 1 shown in FIG. 8, a disk enclosure is comprised of a box-type base 2 with its ceiling open and a cover (not shown) for closing this opening of base 2. In the disk enclosure are provided a predetermined number of magnetic disks 4 that are supported by a spindle motor 3 of a hub-in structure, wherein magnetic disks 4 are rotated by spindle motor 3 at a predetermined speed.
In base 2, there is provided an actuator 5. Actuator 5 is rotatably attached in its mid-section to base 2 via a pivot 6. At the front end of actuator 5 is provided a magnetic head 7 for reading and writing data to magnetic disk 4. At the back end of actuator 5 is provided a voice coil 8. On the other hand, there is also provided in base 2 a stator 9 placed opposite the voice coil 8, wherein voice coil 8 and stator 9 cooperates each other and compose a voice coil motor. The voice coil motor turns actuator 5 on pivot 6 by utilizing the magnetic force which is induced between voice coil 8 and stator 9 by supplying electric current to voice coil 8.
There are prior art stoppers 10, 11 attached to base 2 which regulate a turning range of actuator 5 toward the inside and outside of magnetic disk 4, respectively. Stopper 10, which regulates the turning of actuator 5 toward the inside of magnetic disk 4, has a function for preventing actuator 5 from coming in contact with a top clamp 12 which secures magnetic disk 4 to spindle motor 3 and a function for securing a predetermined positioning accuracy of actuator 5 when writing servo information to magnetic disk 4. On the other hand, stopper 11, which regulates the turning of actuator 5 toward the outside of magnetic disk 4, has a function, particularly in the case of the load/unload type of disk drive that has been widely used recently, for preventing actuator 5 from passing through a ramp 13 which serves to hold magnetic head 7 in its evacuated condition. Furthermore, stopper 11 has a built-in magnet to keep magnetic head 7 stationary on ramp 13, whereby actuator 5 is pulled to stopper 11 by means of the magnetic force.
Conventionally, such a stopper 11 is secured to base 2 by inserting a pin provided on stopper 11 into a mounting hole formed in base 2 or by inserting a boss formed on base 2 into a hole formed in stopper 11. The stopper 10, which serves to regulate actuator 5 turning toward the inside of magnetic disk 4, must be attached to base 2 with high precision. This is because a reference position for writing be in a condition where actuator 5 is up against stopper 10 when servo information is written to magnetic disk 4 using magnetic head 7. Along with the tendency in magnetic disk 4 toward high recording densities, more precise positioning accuracy is now required. For this reason, the attachment accuracy of stopper 10 to base 2 needs be enhanced. Therefore, it is commonly the case that clamp faces or bosses have been formed on base 2 by means of cutting operations.
3. Problems to be Solved by the Invention
The prior art designs prevent the efficiency of manufacturing processes and cost reductions of hard disk drives to perform additional processing of base 2 which is typically cast, in order to form clamp faces or bosses for stopper 10. Moreover, it is problematic to attach two stoppers 10, 11 to base 2, which reduces the efficiency of manufacturing processes, as well. In addition, as downsizing of hard disk drives has rapidly progressed in recent years, it may be difficult to keep space for attachment of stoppers 10, 11 particularly in small-sized hard disk drives.
In view of the above problems, it may be conceivable to integrate two stoppers 10, 11 by linking them together, however, this can not solve all of the problems and consequently there sill remain some problems, such as space limitations and the need of additional processes for ensuring attachment accuracy of those stoppers to base 2.
The present invention is directed to solve those technical problems mentioned above. Therefore, it is an object of the present invention to provide a disk drive unit, a hard disk drive or the like, in which the efficiency of manufacturing processes, cost reductions, and space savings are achieved.